slimsoftball Posted November 15, 2004 Report Share Posted November 15, 2004 There has been alot of talk recently, especially on LS1Tech about good bower cams and of course this got me thinking about it also. I talked to Tim at Lingenfelter Performance about what I had and he recommended their LS-1 GT7 cam. He said drivability would not change much at all. The specs are below. Let me know what you think. Seems a little over the top but I am definately no expert. Camshaft: GT7 Engine type: GM Gen III & Gen IV V8 including LS1, LS6, LS2, LQ4, LQ9 Follower type: Hydraulic roller Intake Exhaust Lobe lift: 0.326” 0.321” Rocker ratio: 1.7:1 1.7:1 Valve lift: 0.554” 0.546” Duration at 0.050: 208 230 Advertised (total) duration:" 261 282 Lobe separation angle: 121.0 I was initially looking at the GT2-3. Lobe lift: 0.336” 0.340” Rocker ratio: 1.7:1 1.7:1 Valve lift: 0.571” 0.578” Duration at 0.050: 207 220 Advertised (total) duration:" 255 281 Lobe separation angle: 118.5 Centerline: 118.5 Link to comment Share on other sites More sharing options...
TBSS Posted November 15, 2004 Report Share Posted November 15, 2004 Ah, the never-ending quest for more. Isn't it divine? Give Terry at Cam Motion a call and tell him what you're after. He knows his stuff, and hooked me up right. Link to comment Share on other sites More sharing options...
slimsoftball Posted November 15, 2004 Author Report Share Posted November 15, 2004 Ah, the never-ending quest for more. Isn't it divine? Give Terry at Cam Motion a call and tell him what you're after. He knows his stuff, and hooked me up right. <{POST_SNAPBACK}> Will do. Don't they do all the grinds for Futral? By the way. I saw that pic of your driveshaft...... Link to comment Share on other sites More sharing options...
TBSS Posted November 15, 2004 Report Share Posted November 15, 2004 Ah, the never-ending quest for more. Isn't it divine? Give Terry at Cam Motion a call and tell him what you're after. He knows his stuff, and hooked me up right. <{POST_SNAPBACK}> Will do. Don't they do all the grinds for Futral? By the way. I saw that pic of your driveshaft...... <{POST_SNAPBACK}> Yes they do Futral's cam work for them. Waiting to hear from the dealer on the driveline. Sure woke some people up standing next to the dyno.... Link to comment Share on other sites More sharing options...
BigTex Posted November 15, 2004 Report Share Posted November 15, 2004 What did they say to turn you off the GT2-3? Personally, I don't like to numbers on the first cam. Of course my personal tastes have nothing to do with making power. I just think there is too much exhaust duration with the GT7 listed. Getting down to the valve events of the two cams, they have some distinct similaries and one major difference: (I'm basing my assumptions off a +2 advance for the gt7, IVO means Intake Valve Opens...) GT7 IVO: -15 IVC: 43 EVO: 58 EVC: -8 GT2-3 IVO: -15 IVC: 42 EVO: 48.5 EVC: -8.5 See the ratio they have there: intake valves open and close virtually the same, exhaust closes basically the same, but the much larger exhaust duration of the GT7 is directly changing the exhaust valve opening. You can see the emphasis on minimal overlap at -23* for both cams (IVO+EVO=overlap). That earlier exhaust opening is what I don't like (58 degrees before bottom dead center). If you have a good exhaust system, you should not have to crutch the exhaust valve that much. By dropping the exhaust duration and holding that exhaust valve closed longer, you'll increase your torque. By opening it too early, you let out cylinder pressure while combustion is still occuring and waste power. Apparently Lingenfelter feels that the intake events and overlap are more important than opening the exhaust valve too early. If you were running stock manifolds, stock exhaust, cats, and wanted high revving big boost, the GT7 might be needed. Link to comment Share on other sites More sharing options...
zippy Posted November 15, 2004 Report Share Posted November 15, 2004 i agree with big tex. the gt-7 does look like the type of cam i'd be going for of the two though. it should pull more rpm than the gt2-3. the gt-7 though is going to take all the boost you can throw at it and keep pulling. i'd like to see some of the dyno numbers they have with them. Link to comment Share on other sites More sharing options...
slimsoftball Posted November 15, 2004 Author Report Share Posted November 15, 2004 What did they say to turn you off the GT2-3? They really didn't say anything to turn me off to the GT2-3. I had read about that cam and called them to ask if they thought it would be a good cam for building/keeping boost with my set-up. That is when he told me the GT7 would be better. Of course not knowing a whole lot about how the events work I really didn't get into a long discussion with him about why he thought the GT7 was better for me. Thanks for all that info in your post. One of these days I may actually start to understand camspeak. I do see your point about the exhaust duration on the GT7 of course it just makes me want to understand why they think it is the better choice even more. Of course I am really no closer to deciding which one of the two to get Link to comment Share on other sites More sharing options...
slimsoftball Posted November 15, 2004 Author Report Share Posted November 15, 2004 i agree with big tex. the gt-7 does look like the type of cam i'd be going for of the two though. it should pull more rpm than the gt2-3. the gt-7 though is going to take all the boost you can throw at it and keep pulling. i'd like to see some of the dyno numbers they have with them. <{POST_SNAPBACK}> I was sort of leaning that way too Zippy (GT7) Not sure why though I will be ordering it sometime in the near future. Probably going with some of the AFR Mongoose heads also. That is of course if I can convince my wife that my daughter needs them for Christmas. Link to comment Share on other sites More sharing options...
zippy Posted November 15, 2004 Report Share Posted November 15, 2004 unless you plan a blower upgrade, i wouldn't do anything to the heads personally at this point. i'm not sure you'd see enough gain out of them to make it worth the $$. Link to comment Share on other sites More sharing options...
slimsoftball Posted November 15, 2004 Author Report Share Posted November 15, 2004 unless you plan a blower upgrade, i wouldn't do anything to the heads personally at this point. i'm not sure you'd see enough gain out of them to make it worth the $$. <{POST_SNAPBACK}> Funny you should say that. Every time I consider buying heads I say the same thing to myself. Then I justify it by saying that sooner or later I will rip of the Radix and build a stroker and will already have heads. Link to comment Share on other sites More sharing options...
BigTex Posted November 16, 2004 Report Share Posted November 16, 2004 Compare your current cam with the GT7. Comp 212/218 115 +2 IVO: -7 IVC: 39 EVO: 46 EVC: -8 So lets see.... Your current cam has 212 degrees of intake duration. The GT7 has 208. Your cam opens the valve a bit sooner, and closes it a tad earlier. Your cam has 218 degrees of exhaust, the gt7 has 230! The gt7 opens the valve alot earlier than yours, but they both close at the same time. So the question becomes, do you need more exhaust flow? Because the gt7 isn't giving you any more intake duration, hence no more power. But the GT7 does open and close the intake valve later, which favors higher rpms. For a cheap test, using your adjustable timing chain, retard your cam 4*. That puts your current cam more inline with the GT cams as far as intake valve events (-11, 43). I think you'll make more power and breathe better in the upper rpms with the 4* retard. Link to comment Share on other sites More sharing options...
slimsoftball Posted November 16, 2004 Author Report Share Posted November 16, 2004 BigTex, Just when I think I am figuring this thing out you go and tell me al I have to do is adjust my timing chain. Thanks again. Someday I will get this thing figured out. Link to comment Share on other sites More sharing options...
SuperSport Posted November 16, 2004 Report Share Posted November 16, 2004 Slim, keep us updated with how the truck feels with the 4 degrees of retard in it. Link to comment Share on other sites More sharing options...
SSLink Posted November 16, 2004 Report Share Posted November 16, 2004 Man, that GT7 has an awfully wide split in duration and an awfully wide LSA to compensate and keep overlap down. LPE has forgotten more about valve timing and cam design than I will ever know but like Big Tex I gotta wonder if you need to crutch the exhaust duration that much on a relatively low boost Radix setup. That wide LSA is going to flatten and extend the power band higher too, probably beyond the 6K RPM that the Eaton blower likes to spin. I also like the higher lifts on the GT2-3. Just my $.02. Link to comment Share on other sites More sharing options...
BigTex Posted November 16, 2004 Report Share Posted November 16, 2004 I'm sure lingenfelter has their reasons for designing that cam. I think they approach those cams like GM would - drivability and emissions being big parts. Many of lingenfelters clients buy a package and expect it to drive like stock, give them no problems, and pass all emissions. slim - You going to retard your cam? Link to comment Share on other sites More sharing options...
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